Sending I-751 Receipt Notice to China, ASC appointment notice?

Does anybody know what the best, most secure, and most cost effective method is for sending this document to my wife? She had to go back to China before the document arrived, so now I need to send it to her. All I can find are USPS services that are at least $50. When I lived in China, my dad sent me something using those USPS services. It was supposed to be fast, but he spent over $80 US for an envelope that literally took three weeks to arrive.

How does one ship with China's EMS here in the States?

Also, does anybody know how soon after someone receives the I-751, the ASC appointment notice for fingerprinting arrives?

And clearly print your wife's cell phone number above the Chinese address. If there is any questions the delivery people have, they can and will call her and get it worked out so it can be delivered promptly. (You do not need the 01186 numbers, just her in country cell number).